From the DreamHost Status Blog:
On Wednesday, March 16th from 10am to 6pm, we will be upgrading Ceph, the underlying storage system of DreamObjects, to a newer version of the “Hammer” release. The new release provides improved performance, increased Swift API compatibility, and fixes numerous bugs. We expect the upgrade process to last only a few hours but we are allowing for additional time for monitoring and tuning.
During the maintenance, DreamObjects could be temporarily unavailable. However, your data stored in DreamObjects will remain safe.
If you have any questions or concerns, please don’t hesitate to contact support for assistance.
Follow the progress on the maintenance on the DreamHost status blog.
UPDATE: We are delaying the maintenance until Monday, March 21st at 10AM. The cluster is still rebalancing after a configuration change and we didn't want to do an upgrade late in the week!